I'm baffled

I have a couple of 'c' object files that send mail when ever there in an 
insert or delete to specified tables.
The problem is that I get the mail message even if the insert fails!

what am I doing wrong?


thanks


The function;
    create function insert_r1(text, text, text, text) returns int4
         as '/var/pgsql/insert_r1.so' LANGUAGE 'c' ;
the rule:
  create rule partmaster_I as
    on insert to partmaster
       do select insert_R1(new.afpn, 'partmaster(insert)','','') as answer;

the 'c' module:
# include "internal/postgres_fe.h"
# include <string.h>
# include <unistd.h>

int insert_r1(text *arg1, text *arg2, text *arg3, text *arg4)
{
  char *table, *key, *mesg, *user;
  char host[20];
  FILE *fp;
 
  arg1->vl_dat[arg1->vl_len - VARHDRSZ] = '\0';
  arg2->vl_dat[arg2->vl_len - VARHDRSZ] = '\0';
  arg3->vl_dat[arg3->vl_len - VARHDRSZ] = '\0';
  arg4->vl_dat[arg4->vl_len - VARHDRSZ] = '\0';

  key   = strdup(arg1->vl_dat);
  table = strdup(arg2->vl_dat);
  mesg  = strdup(arg3->vl_dat);
  user  = strdup(arg4->vl_dat);

  gethostname(host, sizeof(host));
  system(" cat /tmp/newMsg >> /tmp/newMsg.arc");
  if ( (fp = fopen("/tmp/newMsg", "w+") ) == NULL)
    return(-1);
    fprintf(fp, "%s:: %s:(%s) Approval requested  - %s   %s\n", 
host,table,key,mesg,user);
      fclose (fp);

    system("Mail -s \"Bmss \" hook@kcp.com     < /tmp/newMsg");
  return(0);
}